Method and apparatus for surface conditioning ingots and the like



June 20, 1961 B. SPENCER D. METHOD AND APPARATUS FOR SURFACECONDITIONING INGOTS AND THE LIKE Filed Feb. 5, 1958 5 Sheets-Sheet 1 I El I l 51 I I] as BI 75 I 1 INVENTOR.

DONALD B. SPENCER ATTORNEYS June 20, 1961 METHOD AND APPARA INGOTS ANDTHE LIKE Filed Feb. 3, 1958 D B. SPENCER TUS FOR SURFACE CONDITIONING 5Sheets-Sheet 2 ZIA' INVENTOR.

o DONALD B. SPENCER 7 ATTORNEYS June 20, 1961 D. B. SPENC 2,988,966

' METHOD AND APPARATUS FOR SUR CE CONDITIONING INGOTS AND THE LIKE FiledFeb. 3, 1958 5 Sheets-Sheet 3 t no INVENTOR.

DONALD B. SPENCER ZMZW/XMW ATTORNEYS June 20, 1961 D. B. SPENCER2,988,966

METHOD AND APPARATUS FOR SURFACE CONDITIONING INGOTS AND THE LIKE 5Sheets-Sheet 4 Filed Feb. 5, 1958 IHIHIH H! HNIIHHIH 1 l l I 1 INVENTOR.

DONALD B. SPENCER ATTORNEYS June 20, 1961 D. B. SPENCER METHOD ANDAPPARATUS FOR SURFACE CONDITIONING INGOTS AND THE LIKE 5 Sheets-Sheet 5Filed Feb. 3, 1958 INVENTOR.

ATTORNEYS United Stat t? 2,988,966 METHOD AND APPARATUS FOR SURFAC'ECON- DITIONING INGOTS AND THE LIKE Donald B. Spencer, Portland, Oreg.,assignor to Guy F.

Atkinson Company, South San Francisco, Calif., a corporation of NevadaFiled Feb. 3, 1958, .Ser. No. 713,018

19 Claims. (Cl. 90-34) This invention relates to an improved method andmachine for removing surface imperfections in air or vacuum cast metalingots and billets and other heavy work pieces. The class of work towhich the invention chiefly pertains is generally known as ingotscalping and billet surface conditioning.

It has heretofore been the practice to remove such surface imperfectionson a, lathe or by grinding. A lathe operation, however, is relativelyslow and costly, and does not provide the desired rigidity of supportnecessary for a more rapid surface conditioning operation nor doavailable tools provide satisfactory life when cutting the surface skin,particularly on ingots of refractory metals. Grinding also is slow andcostly and for certain refractory metals is not satisfactory oreconomical. The surface imperfections'referred to consist ofdiscontinuities and non-homogeneous structure, roughness, variations inhardness and sometimes impurities commonly extending to a depth ofone-sixteenth to one-half inch. Because of the manner in which the workpiece is supported and rotated, and the eccentric tool loading, a cut ofsuch depth must be made at a feed of .010 inch maximum 011 a lathe andat very low surface speeds. It is, therefore, usually necessary to makea series of cuts in order to remove sufiicient depth of materialtoeliminate all imperfections from the outside of the ingots or billets.Furthermore,only cylindrical work can be machined in a lathe whereby nosatis factory and eflicient machinery exists other than grinders orplaners for the surface conditioning of square, rectangular or octagonalbillets, which shapes are often advantageous for subsequent operationssuch as rolling or forging. 7

It is, therefore, the general object of the present'invention to providean improved method and apparatus for machining heavy workpieces.

Another object is to provide an improved machine for removing surfaceimperfections in ingots and billets, particularly ingots and billets ofthe refractory metals and super alloys.

Another object is to provide an improved machine capable of removinglarge amounts of metal under conditions of extremely low surface cuttingspeeds, low tool and work piece temperatures, and without the use ofcoolants.

Another object is to provide a surface conditioning method and apparatuswhich will operate on square, rectangular or octagonal shapes, as wellas round.

Another object is to provide hydraulic clamping means for positioning aheavy work piece.

Another object is to provide an extremely rigid support for a work piecehaving a feed movement.

Another object is to provide an improved feed movement which is notsubject to variation by torsional or bending deflections in the machine.

Patented June 20, 1961 Another object is to provide a machine of thetype described which feeds the work piece in rectilinear motion withrespect to stationary cutting tools.

Another object is to provide a vertical feed movement for heavy workpieces in a machining operation.

Another object is to provide a surface conditioning machine having aplurality of cutting tools arranged to make a plurality of cutssimultaneously on a work piece. 7

Another object is to provide a surface conditioning machine having aplurality of cutting tools operable simultaneously on. all sides of awork piece to balance the tool loading and minimize deflection in themachine.

Another object is to provide a surface conditioning machine for ingotsand billets which will operate to the full depth of material to beremoved in a single cut in the majority of cases.

Another object is to provide a machine which will support a work piecewith all its longitudinal surfaces available for cutting so that allsides may be finished without relocating the work piece in itssupporting means.

Another object is to provide a machine for the purpose described whereinthe loading from the weight of the work piece and tool pressure is notimposed upon metal bearings as in the case of a lathe.

Another object is to provide a liquid supporting medium for heavy workpieces in a machining operation.

While the present machine is especially designed for removing surfaceimperfections from ingots and billets, it is to be understood that theprinciples of the invention may be applied to other machining operationswhere similar problems arise. The invention is, therefore, notto belimited to use on ingots and billets, as the features of the presentconstruction may be utilized to advantage in the machining of stillother types of work pieces.

, In the practice of the present invention, the ingot or billet ischucked and clamped between two opposed pistons or rams which aremovable by the action of hydraulic pressure in a pair of cylinders toprovide a rectilinear working stroke. In the illustrated embodiments,the work piece is stroked vertically between upper and lower verticalcylinders but the cylinders may be disposed horizontally to impart ahorizontal stroke if desired. In the illustrated embodiments, the weightof the work piece is supported on the lower piston whereby the machineis without bearings or frame members subject to loading and deflectionin the conventional manner. While one piston is advanced in feedmovement by hydraulic pressure, the movement of the other piston issubject to hydraulic restraint suflicient to hold the work piece rigidlybetween the two pistons.

A plurality of cutting tools are mounted in symmetrical arrangementaround the piston axis to engage the work piece simultaneously onopposite or all sides thereof. In

' this manner the tool loading on the work piece is essentiallybalanced, whereby the usual deflection produced by a single tool iseliminated. Thus, the major forces which give rise to objectionabledeflection in conventional equipment are balanced or neutralized so thatcuts can from the following specification and drawings which describeand illustrate two embodiments of machine for carrying out the method ofthe invention. It is to be understood, however, that the invention maytake other forms and certain features may be used without others asvarious changes in the construction and arrangement of parts will occurto persons skilled in the art. All such modifications within the scopeof the appended claims are included in the invention.

In the drawings:

FIGURE 1 is a side elevation view of a first embodiment of theinvention, certain parts being'shown in section;

FIGURE 2 is a sectional view in reduced scale of the machine shown inFIGURE 1', taken on the line 2-2 of FIGURE FIGURE 3 is a side elevationview at right angles to FIGURES 1 and 2;

' FIGURE 4 is a cross sectional view taken on the line 4-4 inFIGURE 1;

' FIGURE 5 is a cross sectional view taken on the line 55 in FIGURE 1;

FIGURE 6 is a sectional view of a tool holder taken on theline' 6'6 ofFIGURE 5;

FIGURE 7 is a sectional view of a tool holder taken on the line 77 ofFIGURE 5;

FIGURES 8-11 are diagrams showing positions of the pistons and workpiece in successive stages of operation;

FIGURE 12 is a plan view of a work piece after a number of cuts havebeen made;

FIGURE 13 is a fragmentary sectional view of a modification having arotary tool holder block;

FIGURE 14 is a fragmentary bottom plan view of the tool holder blockshown in FIGURE 13;

FIGURE 15 is an enlarged view of certain details of FIGURE 13 showing atool holder in cutting position; and

FIGURE 16 is a view similar to FIGURE 15 showing the tool holder pivotedto non-cutting position.

Embodiment in FIGURES 1 to 7 Y The machine illustrated in the drawingscomprises a pair of heavy and rigid upright frame members 10, preferablysecurely fastened by suitable anchor bolts to a concrete foundation 11on opposite sides of a well 12. Projecting downwardly into the well 12is a cylinder 13 equipped at its upper end with a liner 14 and suitablesealing means to slidably receive a cylindrical lower piston or ram, 20.On the upper end of cylinder 13 is an integral rectangular supportingframe 21 bolted or otherwise se-' cured to the upright machine frames10. Frame 21 has horizontal flanges 21A engaging in grooves in the framemembers to form a positive interlock between the parts. The lower end ofthe cylinder is connected with a pipe for the admission and relief ofhydraulic fluid.

The upper end of ram projects out of cylinder 13 and is connected with aworm gear 22 which may be turned by a worm 23 to rotate the ram in thecylinder. Worm 23 is fixedly mounted on a shaft 24 having suitableoperating means such as hand wheel 25. Worm shaft 24 is mounted forrotation in bearing brackets 26 on a rectangular guide plate 27 whichslides up and down with the ram in vertical guides 28 on the uprightframe members 10, as shown in FIGURE 4. In the lowermost position ofguide plate 27 its feet 27A rest on a flat top surface of frame 21. Theram and worm gear 22 rotate relative to plate 27 when worm 23 is turned,whereby, when the worm is set in adjusted position, the ram cannotrotate. A chip collecting pan 29 rests on guide plate 27.

Mounted on the upper end of ram 20 is a hardened steel holding shoe 30having upwardly projecting teeth in its top surface to engage andsupport the ingot or billet A. A vertical bore in the center of shoe 30contains a center point 31 which is pressed upwardly above thesupporting surface of the shoe by a spring 32 in the bore. This centerpoint is used for locating a central depression formed in the bottom endof the ingot in the center of the shoe 30' which, by reason of itscentral bore, is annular in shape and concentric with the vertical axisof ram 20. Thus, the center point 30 is precisely on the ram axis and aningot having a bottom depression in the geometrical center of a squarecut bottom surface will be in balance on the supporting shoe.

Bolted or otherwise secured to the upper ends of upright frame members10 is a central frame structure 35 carrying on its lower end a toolholder block 36. Frame 35 has horizontal flanges 35A engaging in groovesin the frame members 10 to form a positive interlock between the parts.On the uper frame 35' is mounted an upper vertical cylinder 37 which inthe present embodiment is of less diameter than the lower ram 20. Uppercylinder 37 is equipped with a piston 38 carrying a cylindrical ram 40of smaller diameter than the piston. The lower side portion of ram 40 isequipped with a suitable guide member 41 slidable in guide means in acentral opening in tool holder block 36 and a central vertical opening42 in frame 35 to provide lateral rigidity for the lower end of ram 40.Guide member 41 in the present instance is circular, whereby the ram 40and piston 38 may rotate.

The lower end of ram 40 is equipped with a hardened steel holding shoe43 having a projecting center point 44 similar to the lower center point31. Center point 44 is used to locate a conical recess in thegeometrical center of the top end surface of the ingot on the axis ofram 40 and cylinder 37 which is in alignment with the axis of lower ram20 and cylinder 13. Opening 42 and the central opening in the toolholder block 36 are of suflicient size to admit a work piece A slightlylarger than ram 40.

Shoes 30 and 43 are smaller in diameter than the work piece so as not toengage the cutting tools presently to be described when the ends of thework piece travel beyond the cutting tools at the end of each stroke.

The upper end of cylinder 37 is connected with a pipe 45 for hydraulicfluid and the lower end is connected with a similar pipe 46. Just belowthe connection with pipe 46 is a ring seal 47 around the ram 40. Byreason of the fact that ram 40 is of smaller diameter than piston 38,hydraulic fluid introduced through pipe 46 will raise the piston andram.

- Referring now to FIGURES 5, 6, and 7, the tool holder block 36 isequipped on its under side with guideways 48 for a plurality of toolholders 49. For machining a cylindrical work piece, the guideways 48 aredirected radially toward the common ram axis, and each tool holder49carries a radially directed cutting tool 50. The tool is held inadjusted position in the tool holder by means of adjusting screw 51 andclamp screws 52.

Each tool holder 49 is equipped with a cross slot 53 engaged by aneccentric head 54 on a stub shaft 55 journaled in block 36. Each stubshaft 55 carries a small spur gear 56. The four gears 56 associated withthe four tool holders shown in FIGURE 5 may be rotated simultaneously bya ring gear 60 which is rotatable on a cylindrical bearing surface 61 inblock 36 concentric with the ram axis. Ring gear 60 isrotated by apinion 62 connected with a suitable operating device such as handle 63.Thus, by swinging the handle 63 in one direction, all the tools 50 maybe simultaneously retracted to clear the work piece, and by swinginghandle 63 in the opposite direction, the tools are advanced intoposition for a cut. Suitable stop means, not shown, are provided toplace the tools in proper cutting position when handle 63 is swung tothe limit of its movement. The tools 50 preferably have an adjustablecutting position as determined by adjusting screws 51 and are usuallynot advanced for successive cuts as in most conventional machines forthis purpose. It is within the scope of the invention, however, toprovide means whereby the operator can infeed all the toolssimultaneously for a deeper cut it necessary. More than four toolholders may be provided, and, in any case, all the tools cutsimultaneously in each working stroke of the work piece.

Hydraulic system The hydraulic system for stroking the work piece isillustrated schematically in FIGURE 2 for convenience of explanation. Afirst pump 70 withdraws hydraulic fluid from reservoir tank R to supplya pressure pipe 72. Pressure pipe 72 connects with a valve 74 on thepipe 15. Pipe 15 is also connected with a pressure gauge 75.

A second pump 71 withdraws hydraulic fluid from reservoir R to supply apressure pipe 73. Pressure pipe 73 has a branch 76 connected with avalve 77 leading to the pipe 46. Another branch of pressure pipe 73connects with a valve 78 connected with a pipe 79. Pipe 79 is in turnconnected with a valve 80 leading to the pipe 45 which is equipped witha pressure gauge 81.

It is understood that both pumps are equipped with the usual by-passvalves (not shown) which may be adjusted to produce the same ordifferent maximum working pressures in pressure pipes 72 and 73. Thepumps are adapted to operate continuously to supply hydraulic fluid tosaid pipes as needed, the pumped fluid being by passed to the reservoirafter the predetermined maximum pressures are established. r

A return pipe 85 is also connected with the reservoir tank R. Valve 74in one position connects cylinder 13 with pressure pipe 72 and in asecond position it connects the cylinder 13 directly with a branchreturn pipe 86. In a third position the valve 74 connects the cylinderwith a pipe 87 which passes the discharge from cylinder 13 through anadjustable pressure relief valve 90 to the return pipe 85.

Another branch 91 of return pipe 85 is connected through a valve 92 withpipe 46. The valves 77 and 92 permit pipe 46 to be connected with eitherthe pressure pipe 73 or return pipe 85.

Return pipe 85 is further connected with a pipe 93 leading to valve 80,and to an adjustable relief valve 95 connected through a pipe 96 to thepipe 79. Valve 80 thereby permits pipe 45 to the connected directly withreturn pipe 85 by Way of pipe 93 or to pipe 79. When valve 80 is turnedto the position shown in FIGURE 2 connecting pipe 45 with pipe 79, thevalve 78 may be opened to supply fluid to pipe 45 at a maximum pressuredetermined by the adjustment of relief valve 95. When valve 78 is closedit will be appreciated that relief valve 95 will maintain pressure inpipe 45 only when piston 38 is moving upward. The importance of thisfeature of selective control will be explained in connection with theoperation of the machine.

When valve 80 is rotated a quarter turn counterclockwise, the source ofpressure is cut off from pipe 45 and the flow from this pipe, if it iscarrying discharge from cylinder 37, is shunted around pressure reliefvalve 95 to discharge the cylinder directly into return pipe 85 atapproximately atmospheric pressure.

The schematic hydraulic diagram in FIGURE 2 shows the essential valveand piping connections in simplified form for convenient explanation ofthe operation of the system. In practice the manually operable valvesare ganged together in two multiple valve units 98 and 99 for operationby a pair of-hand-les 100 as shown in FIGURE 1. It is also within thescope of the invention to provide power operating devices for such valveunits responsive to the movements of the work piece, and otherrefinements, for automatic operation.

The difference in the diameters of ram 20 and piston 38 permits the useof a single pump hydraulic pressure system if desired. The same unitfluid pressure applied to both upper and lower cylinders produces asuperior force on the lower ram to overcome tool resistance and theweight of the Work piece and move the work piece upward. There are alsocertain operational advantages in a single pressure system which may beutilized.

The present two pump system, however, has the. advantage of maintainingconstant clamping force on the work piece regardless of tool resistanceor piston velocity. It will be appreciated that with valve in theposition shown in FIGURE 2 and valve 78 open during the upward workingstroke, the clamping force on the work piece is determined solely by theadjustment of relief valve 95. This clamping force will not be reducedby excessive tool resistance even to the point of stopping the movementof the work piece.

Another important advantage of the two pump system is that it permitsthe use of upper and lower cylinders of equal diameter since theadjustment of pressure relief valve does not limit the maximum pressureavailable from pump 70 to drive the lower ram- 20. In large machinerythe saving by making both cylinders the same size may more than oif-setthe cost of the second pump.

In any case, the point to be emphasized is the inherent flexibility ofthe present machine in regard to the variables mentioned whereby variousmodifications within the scope of the invention may be utilized to thegreatest advantage for the particular work to be done.

Operation The method of the invention and the operation of the machineand hydraulic system will now be described with reference to FIGURES 2and 8-12. The ingot A will be used as an example of a work piece to besurface conditioned.

The ingot or billet is first prepared by cutting the ends 01f flat inplanes perpendicular to its longitudinal axis. Then conical depressionsare cut in the centers of the top and bottom surfaces to receive thecenter points 3 1 and 44.

Before the ingot A can be placed in the machine, the lower ram 20 mustbe retracted downward and the upper ram 40 must be retracted upward.This is accomplished by manipulation of the valves shown in FIGURE 2.Valve 74 is turned to the position shown, connecting pipe 15 with returnbranch pipe 86 whereupon ram 20 and work holding shoe 30 will drop bygravity to the lower position shown in FIGURES 2 and 8. Upper ram 40 israised by closing valve '92 and opening valve 77 to admit pressure tothe lower end of cylinder 37 under piston 38. Valve 80 is turned toconnect pipe 45 with pipe 93 for free discharge from the upper end ofthe cylinder.

The ingot is then placed in position on lower work holding shoe 30 andheld steady while the upper ram 40 is brought down, as shown in FIGURE8, to engage center 92 and, at the same time, turning the valve 80 tothe posi tion shown in FIGURE 2 to connect pipe 45 with pipe 79.Pressure is admitted to pipe 79 by opening valve 78. The ingot isthereby clamped between the work holding shoes 30 and 43.

The tools 50 are then projected to cutting position by lever 63.

To make the first cutting stroke, valve 74 is turned to connect the pipe15 with pressure pipe 72 causing the lower ram 20 to move upward, asshown in FIGURE 9. Valve 77 is left closed and valve 92 is left open.Valve 78 is closed and valve 80 is left in the position shown in FIGURE2 whereby fluid from the upper end of cylinder 37 is discharged throughrelief valve 95. The adjustment of this relief valve determines theclamping pressure on the ingot as long as the ingot is moving upward.This clamping pressure is not diminished by the tool resistance. It isevident, however, that, if the upward movement of substantiallyreleased.

When it is desired to maintain clamping pressure even.

stop, valve 78 may be left open to maintain the upper end of cylinder 37in communication with the source of pressure in pipe 73. Fluid displacedfrom the upper end of cylinder 37 will then be discharged through reliefvalve 95 and, if valve 95 is adjusted to release at a pressure lowerthan that developed by pump 71, some fluid from the pressure pipe willalso flow'back through valve 95. Constant clamping force is therebymaintained regardless of tool resistance and even if'the tool resistanceshould stop the upward movement of the ingot.

In FIGURE the ingot has almost completed its upward cutting stroke andis ready for its downward return stroke. When the lower edge of theingot has cleared the tools 50, the latter are retracted by Swinging thehandle 63 and the valves adjusted for return stroke.

' In order to maintain clamping pressure on the work piece during thedown stroke, valve 74 is turned to conn'ect pipe with pipe 87 leading torelief valve 90. With valve 80 left in the position shown in FIGURE 2,valve 78 is opened, it it is not ready open, to introduce pressure tothe upper end of cylinder 37 causing upper ram 40 to push the work pieceand lower ram downward. The maximum pressure which can be established inthe upper end of cylinder 37 on the down stroke is determined by theadjustment of relief valve 95 which was made for the up stroke, as abovedescribed. Relief valve 90, which functions only on the down stroke, isaccordingly adjusted to open at a relatively low pressure to produce thedesired clamping force on the down stroke, taking into consideration thepressure setting of valve 95 and the different piston areas in cylinders13 and 37. Less clamping force is required on the return stroke than onthe working stroke. Valve 92 remains open for free discharge from thelower end of cylinder 37. The return stroke just described isillustrated in FIGURE 11.

After the upper end of the ingot has dropped below the level of tools50, the tools are returned to cutting position by means of lever 63 andthe entire assembly of the two rains and ingot is rotated to a newcutting position by means of hand wheel 25. Clamping shoes 30 and 43 areof suflicient length to allow the over travel necessary for the ends ofthe ingot to clear the tools 50 in both directions of movement as abovedescribed since the sliding guides 27 and 41 are wider than the ingotand cannot themselves pass the tools 50.

The second upward stroke begins as soon as valve 74 is turned to connectpipe 15 with pressure pipe 72 by reason of the difference in end areasof ram and piston 33. On the second up-stroke valve 80 remains in theposition shown in FIGURE 2 and valve 78 may be closed or left open asexplained in connection with the first Working stroke.

In each working stroke the four tools 50 make four longitudinal cuts onopposite sides of the ingot to the full depth of the imperfections to beremoved, as shown in FIGURE 12. The radial lines C C C and C indicatethe tool center line positions relative to the ingot in four successivecutting strokes. It will be apparent that relatively few cutting strokesare necessary to remove the entire surface of the ingot. In scalpinglarge ingots, a larger number of tools may be employed to advantage. Alarger number of tools not only speeds up the work but also moreeffectively balances the tool loading on the ingot since the resistanceof each tool tends to fluctuate in value in cutting metals of variablehardness.

When the scalping operation is completed, the ingot is returned to itslowermost position, and the upper ram is then raised out of the way forremoval of the work piece. The upper ram is raised by rotating valve 80a quarter turn counterclockwise from its FIGURE 2 position to connectpipe 45 with return pipe 93 and then closing valve 92 and opening valve77 to admit fluid pressure under piston 38. 4

. 8 Modification in FIGURES 13 to 16 FIGURES 13 to 16 illustrate amodified arrangement in which the tool holder block rotates to place theplurality of tools in different cutting positions. Inthis modifica tionthe lower piston assembly is the same as shown in FIGURE 2 except thatworm 23 and worm gear 22 are omitted and ram piston 20 is secured toguide plate 27 whereby the work piece is held securely against rotationby the vertical guides 28. It is not necessary, however, to remove theworm 23 and Worm gear 22 from the machine of FIGURE 2 in order toinstall the' modified tool holder block since the worm itselfconstitutes a rotational lock for the work piece.

The work piece is stroked back and forth without turning, and, aftereach working cut, an annular tool holder block is rotated slightly in anannular channel 151 in the lower end of upper frame member 35. Toolholder block 150 is rotated by means of sprocket teeth 152 on itsperiphery engaged with an endless chain 153. Chain 153 is moved by asmall sprocket wheel 154 on a vertical shaft 155 equipped with a handwheel 156 or other suitable driving means.

Annular channel 151 is adapted to receive different types of tool holderblocks interchangeably according to the character of the work piece andthe choice of the operator. The tool holder assembly has been omittedfrom the channel 151 in the left side of FIGURE 13 in order to show moreclearly how the channel is arranged to accommodate the complete toolholder assembly as a detachable and interchangeable unit. One form oftool holder assembly will be described in detail.

The tool holder block is indexed to each new cutting position by meansof a second ring of peripheral teeth or notches 157 arranged forengagement by a lock pin 158. The inner end of lock pin 158 forms apiston in a cylinder 159 into which fluid pressure may be introduced bypipe 160 to extend the lock pin. A stem on the lock pin is equipped witha spring 166 to retract the lock pin when fluid pressure is relievedfrom cylinder 159.

Each individual cutting tool 50 is secured in a tool holder comprising aclapper box 170 mounted on a pivot 171 in tool holder block 150 andincluding a tail piece 172. Directly above tail piece 172 is acylindrical bore 173 in the tool holder block containing a piston 174.When fluid pressure is introduced into cylinder 173, piston 174 isdriven downward to engage tail piece 172 and hold the clapper box upagainst the under side of tool block 150 so that tool 50 is placed inhorizontal position for a cutting stroke, as shown in FIGURES 13 and 15.

When fluid pressure is relieved from cylinder 173, the weight of theclapper box 170 and tool 50 causes these parts to drop to an inclinedposition, as shown in FIG- URE 16, so that the tool will clear the workpiece when the work piece makes its return stroke downward. If theclapper boxes do not drop by gravity, they are pushed out of the way bythe descending work piece, it being remembered that the bottom end ofthe work piece finishes its upward working stroke at a position slightlyabove the level of tools 50.

In order to provide for rotation of annular tool holder block '150, thechannel 151 is lined with three stationary bearing rings 180, 181, and182 of suitable bearing material. Rings and 182 are secured to framemember 35 by screws (not shown) through their horizontal flanges. Toolholder block 150 is retained in the bearing rings by suitable retainingmeans (not shown) which permit its convenient removal forinterchangeability as above mentioned.

Each cylinder bore 173 communicates with a radial duct 183 leading to anannular channel 185 extending around the outer periphery of therotatable tool holder block 150. Hydraulic fluid is introduced intochannel.

openings in frame members and 35 and bearing ring 180, 'asshown. Thesedetails are shown inFIGURE 15.

Fluid pressure pipes 160 and 186 may be supplied from'o'ne of the pumps70 or 71 in lF' IGURE 2 or from a separate source of pressure undercontrol of suitable valves. When fluid pressure is applied to pipe 186,all the clapper boxes 170 are moved to working position, as ShJOWll inFIGURES l3 and 15, and when fluid pressure is relieved from pipe 186,all the clapper boxes are free to drop to non-working position, as shownin FIG- URE 16. Suitable seals such as rubber O-rings (not shown) may beinstalled in tool holder block 150 above and below channel 185 toprevent leakage of hydraulic fluid from this channel.

Rotatable tool holder block 150 is illustrative of a suitable type ofcross feed for cylindrical work pieces. In a somewhat similar manner theindividual tool holders may be provided with a suitable horizontal crossfeed mechanism for removing the surface imperfectionson polygonalbillets, the work piece being reciprocated up and down by the pistonswithout rotation. In the BIG- URE 13 modification, the stroking cycle isthe same as shown in FIGURES 8 to 11, but without turning of the workpiece. The cutting pattern is similar to FIG- URE 12 except that morecuts are made in each stroke.

. In all'cases the entire lateral surface may be finished in a singleoperation without re-locating the work piece in its holding shoes. Byreason of the fact that the work piece is supported at its ends byholding shoes of smaller size that the end areas of the work piece, alllongitudinal surfaces of the work piece are available for cutting. Whenthe work piece is cylindrical, relative circumferential tool feed may beobtained either by rotating the work piece as shown in FIGURE 2 or byrotating the tool holders as shown in FIGURE 13.

The present arrangement permits the use of a relatively large number oftools operating simultaneously to remove the surface of a large ingot ora billet in a relatively short time. The tool holder block 150 in FIG-URES 13 and 14 carries twelve clapper boxes 170 each holding one tool50.

In the present machine there is no tool feed toward the work piecebecause the tools plow to the full depth of the material to be removedin each out. However, infeed means acting on all the toolssimultaneously may be provided, if desired, as, for example, in removingthe taper from a slightly tapered ingot. Suitable adjustment is, ofcourse, provided in any event to position the tools and advance them incompensation for wear as by individual adjustment screws 175 and clampscrews, not shown.

It will be appreciated that the present machine has no bearings or guidesurfaces subject to excessive loading to produce objectionabledeflection or friction, either by the weight of the work piece or thetool force exerted thereagainst. The weight of the work piece, as wellas the clamping pressure applied thereto, are sustained directly by thehydraulic fluid in the cylinders by reason of the vertical position ofthe cylinders. Lateral, as well as longitudinal, tool pressures aresubstantially balanced on opposite sides of the work piece. Hence, anydeflection or distortion that may occur in the machine is symmetricallyapplied and distributed about the axis of the work piece in bothlongitudinal and transverse directions without aifecting therelationship of the tools to the work.

This is in distinct contrast to a conventional lathe operation, forexample, where the work piece is supported by bearings which mustadditionally sustain eccentric loading applied usually by a single tool.Also, in a lathe, if the chucks are arranged to exert axial clampingpressure on the ends of the work piece, this force likewise introducesadditional loading on the bearings.

The present supporting and moving mechanism for the work; piece and theSymmetrical mounting arrangement of the cutting tools provide suchextreme rigidity against longitudinal, transverse and torsionalmovements and deflections that the tools can successfullyremove-materials at a much faster rate than in conventional machines.Conventional work piece and tool holding arrangements produce chatteringand short tool life when high cutting The mode of material removal inthe present machine is characterized as a deep plowing action at lowcutting speed and very high tool forces wherein a greater volume ofmaterial is removed in unit time by each tool than can be removed by alathe tool, particularly in the case of refractory metals. In order toaccomplish this result the individual unit tool forces provided in thepresent machine are twenty-ifive or more times those provided in aconventional lathe. Although the cutting speed may be only one-tenth thecutting speed of a lathe, the thickness of material removed in each cutmay be twentyfive, or more, times the thickness of material turned offby aiathe in terms of feed rate. Thus, in unit time, each tool mayremove two and one-half, or more, times the volume of material removedby the same tool in a lathe. As a practical example of the efliciency ofthe present machine, a titanium ingot 30 inches in diameter and 96inches long usually requires 16, or more, hours for scalping on a lathe.The same job can normally be done on the present machine in less thanone hour using 12 cutting tools operating simultaneously, and the savingin time is only one of several advantages gained. There are also savingsin power, tool wear and general wear on the machine.

The advantages of the present method and apparatus are strikinglydemonstrated in the scalping and surface conditioning of ingots andbillets of the refractory metals and super alloys. In the case oftitanium, ziroconium and the other refractory metals, for example, it isdilficult or impossible to use conventional grinding methods forremoving surface imperfections. or billets of such metals, as well asthe super alloys known in the trade as M-25Q, A-286, Waspaloy, andothers,

are diflicult or impossible to scalp in a conventional lathe. Suchingots and billets have a surface skin consisting of hard and abrasiveconstituents in the case of the refractory metals, and super hardmartensitic particles in the case of the super alloys, as well asdiscontinuities, porosities and, in the case of air-cast ingots andbillets, inclusions from the mold surface. All of these elements invarying degrees act to create a hard, tough and abrasive skin surfacewhich, unlike the parent metal beneath the surface, resists conventionalcutting methods and causes cratering destruction of the tools.

These difliculties are overcome in the present machine by the deepplowing action of a plurality of tools operating simultaneously onopposite sides of the work piece in balanced loading with rectilinearmovement of the work piece in a massive and rigid supporting structure.Ingots and billets of the above-mentioned refractory metals and superalloys are successfully scalped and surface conditioned in the presentmachine. In the case of ordinary steels, the invention offers theadvantages of speed and economy over conventional methods and apparatus.

Notwithstanding the various advantages herein assigned to verticalchucking and vertical feed movement of the work piece, it is,nevertheless, within the scope of the invention to mount the cylindershorizontally for horizontal reciprocation of the pistons and work piece.It

Further, ingots aosaoe 11 is recognized that there are also certainhorizontal arrangement.

' .Having now described my invention and in what man.- ner the same maybe used, what I claim as new and desire to protect by Letters Patent is:

1. Apparatus for machining a work piece comprising a pair of holdersaligned on an axis of reciprocation to engage opposite ends of the workpiece, opposed fluid pressure actuated pistons connected with therespective holders, a fluid pressure system including a source of fluidpressure and means for applying adjustable fluid pressure to saidpistons to force the holders toward the work piece and thereby to clampthe same between the holders, said holders constituting the sole supportfor said work piece, means in said fluid pressure system controlling thefluid pressure on at least one of said pistons to cause reciprocalmotion of said holders, said first named means serving to continueapplication of clamping force to the work piece during suchreciprocation, tools arranged to make axial cuts simultaneously onopposite sides of the work piece when the work piece is reciprocated,and means for effecting incremental relative rotation between said toolsand work piece about said axis between successive working strokes of thework piece.

2. Apparatus for machining a work piece comprising a pair of holdersaligned on an axis of reciprocation to engage opposite ends of a workpiece, opposed hydraulic pistons connected with the respective holders,an hydraulic system including a source of hydraulic pressure and meansfor applying hydraulic pressures to said pistons to clamp the work piecebetween said holders, said holders constituting the sole support forsaid work piece, means in said hydraulic system controlling thehydraulic pressures on said pistons to cause one holder to advance ineach direction of stroke and push the other holder in retreat, means formaintaining hydraulic back pressure against the piston of the retreatingholder to clamp the work piece against the advancing holder in bothdirections of stroke, tools arranged to make axial cuts simultaneouslyon opposite sides of the work piece when the work piece is reciprocated,and means for effecting incremental relative rotation between said toolsand work piece about said axis after a working stroke of the work piece.

3. Apparatus as defined in claim 2, said means for maintaining backpressures against said pistons comprising pressure relief valvesconnected to control the displacement of hydraulic fluid by retreatmovement of said pistons.

4. Apparatus as defined in claim 2, said means for maintaining backpressure further including said means for applying hydraulic pressuresto said pistons from said source of hydraulic pressure.

5. Apparatus for holding and reciprocating a work piece comprising apair of holders aligned on an axis of reciprocation to engage oppositeends of the work piece, opposed hydraulic pistons connected with therespective holders, an hydraulic system including a source of hydraulicpressure and means for applying hydraulic pressures to said pistons, andmeans for controlling the application of said pressures to said pistonscausing one holder to advance and push the other holder in retreat in astroke in one direction and then causing said other holder to advanceand push said one holder in retreat in a stroke in the oppositedirection, said controlling means further including means formaintaining hydraulic back pressure against the piston of the retreatingholder to clamp the work piece against the advancing holder in bothdirections of stroke.

6. Apparatus as defined in claim 5, one of said pistons being a doubleacting piston for retraction to unclamp the work piece.

7. Apparatus as defined in claim 5, said source of hydraulic pressurecomprising a first source for actuating advantages in a the piston forone or said holders and a second source for actuating the piston for theother holder.

8. Apparatus as defined in claim 2, said rotating means being operableon one of said holders to rotate the work piece.

9. Apparatus as defined in claim 2, said rotating means being operableon said tools.

10. Apparatus as defined in claim 2, one of said holders moving the workpiece in a working stroke and the other holder moving the work piece ina non-working return stroke, the piston area for producing said'workingstroke being greater than the piston area for producing said returnstroke.

11. Apparatus as defined in claim 10, said axis of reciprocation beingvertical, said one holder having the larger piston area clamping thebottom of the work piece and said other holder having the smaller pistonarea clamping the top of the work piece.

12. Apparatus as defined in claim 2, the piston connected with one ofsaid holders being a single acting piston and the piston connected withthe other holder being a double acting piston.

13. Apparatus for machining a work piece comprising a pair of holdersaligned on an axis of reciprocation to engage opposite ends of a workpiece, opposed hydraulic pistons connected with the respective holders,a source of hydraulic pressure operable on said pistons to clamp thework piece between said holders, said holders constituting the solesupport for said work piece, an hydraulic system having valves forcontrolling the hydraulic pressures on said pistons to reciprocate saidpistons with said work piece clamped therebetween, tools arranged tomake axial cuts simultaneously on opposite sides of the work piece whenthe work piece is reciprocated, and means for cffecting incrementalrelative rotation between said tools and Work piece about said axisafter each working stroke of the work piece, said source of hydraulicpressure including means for applying different hydraulic pressures tothe pistons for the two holders and for varying the values of saidpressures individually, and said hydraulic system including valves fordisconnecting the source of hydraulic pressure from said pistonsselectively and means for maintaining predetermined back pressuresagainst said pistons when said source is disconnected and for varyingthe values of said back pressures individually.

14. Apparatus for machining a work piece comprising a pair of cylindersin vertical axial alignment, a single acting piston in the lowercylinder and a double acting piston in the upper cylinder, opposed workholding shoes on said pistons for clamping the ends of a work piece, asource of hydraulic pressure, an hydraulic system having pipeconnections with said cylinders for applying hydraulic pressures fromsaid source to said pistons for clamping a work piece between saidholding shoes, valves in said system for controlling the application ofhydraulic pressures to said pistons to reciprocate said pistons withsaid work piece clamped therebetween, means in said system formaintaining hydraulic back pressure on the retreating piston in eachdirection of reciprocation, a tool holder having axial cutting toolsoperable on opposite sides of the work piece when the work piece isreciprocated, and means for turning the work piece in incrementalrotation relative to said tools after each working stroke of the workpiece.

15. Apparatus as defined in claim 14, said turning means being operableon one of said pistons to rotate said piston in said cylinder.

16. Apparatus as defined in claim 14, said turning means being operableon said tool holder to rotate said tool holder about the axis of saidcylinders.

17. Apparatus as defined in claim 14, said means for maintaining backpressures on said pistons comprising pressure relief valves controllingthe discharge of hydraulic fluid displaced by the retreating piston.

18. Apparatus as defined in claim 14, said lower cylinmemes der andpiston being of larger diameter than said upper 1,973,801 Dustan Sept.18, 1934 cylinder and piston. 2,127,210 Dunbar Aug. 16, 1938 19.Apparatus as defined in claim 14, said source of 2,345,973 HarringtonApr. 4, 1944 hydraulic pressure comprising a first source connected to2,399,824 Pressman May 7, 1946 said lower cylinder and a second sourceconnected to said 5 2,596,772 Hawkes May 13, 1952 upper cylinder. ,52,787,698 Schlatter Apr. 2, 1957 2,875,718 Bieri Mar. 3, 1959 ReferencesCited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS 1573 454 1 752,717 Great Britain -1.- July 11, 1956 Shut 16, 1926 906880Germany Mar. 18 1954 1,956,618 Kamp May 1, 1934

